Expandable device, particularly for internal combustion engines



1956 H. K. LINKS ETAL 2,757,653

EXPANDABLE DEVICE, PARTICULARLY FOR INTERNAL comausnow mamas Filed Aug. 28, 1953 7 a: 73 a g: a a 2 2- 52 a? a6 86 85 0'7 x m 7 g E Q q Q f i a Jaaen/ans HEINRICH K.LINKS, HANS PAULING :1 ROBERT .1.wmsc|-|ms. av

ATT RNEYS 2,757,653 Patented Aug. 7, 1956 EXPANDABLE DEVICE, PARTICULARLY FOR INTERNAL COMBUSTION ENGINES Heinrich K. Links, Ober Ramstadt, near Darmstadt, Hans Pauling, Eislingen (Fits), and Robert J. Wirsching, Kornt'al, Germany, assignors to Daimler-Benz Aktiengesellschaft, Stuttgart-Untermrkhelm, Germany Application August 28, 1953, Serial No. 377,148

Claims priority, application Germany September 1, 1952 3 Claims. (Cl. 123-90) Our invention relates to an expandable device for automatically taking up lost motion in valve actuating linkages, particularly for internal combustion engines. More specifically, our invention relates to a device comprising a pair of telescopic elements confining an expandable chamber between them and surrounded by a jacket of pliable material, a conduit including a check valve leading from the interior space of the jacket to the expandable chamber, the latter, the conduit and the jacket being filled with a liquid.

it is an object of the present invention to provide a simple and reliable leak-proof attachment of the jacket to the telescopic elements. Further projects are to so correlate the various elements that the jacket will be subjected in operation to a minimum of stresses so as to guarantee a reliable operation and a long life. Further objects are to provide the device with suitable means whereby the operating space may be easily filled with liquid after the device has been completely assembled and after both ends of the jacket have been fixed and sealed to the telescopic elements.

Further objects of our invention will appear from a preferred embodiment of our invention which will be described hereinafter in detail, the accompanying drawing showing a sectional view of the cylinder head and the cam shaft of an internal combustion engine having a valve linkage equipped with our novel self-adjusting device.

The linkage includes a two-armed lever 52 mounted for oscillation about a horizontal axis 53, one arm of such lever being acted upon by a push rod 54 and the other arm acting on stem 55 of a valve 56. It is to be understood, of course, that each cylinder of the engine is provided with two sets of such elements 52, 54, 55.

The push rods 54 of the engines are acted upon by cam 57 of a common cam shaft 58. A spring 59 surrounding stem 55 tends to keep valve 56 closed.

Means are provided for automatically adjusting the location of axis 53 to eliminate any lost motion in the linkage composed of rod 54 and lever 52. For that purpose, the lever 52 is provided with a semi-spherical depression 60 engaged by the depending semi-spherical head 61 of a self-adjusting device composed of a pair of telescopic elements 62 and 63.

The element 62 constitutes a piston on which the cupshaped element 63 is slidably guided, both confining between them an expandable chamber 64 in which a spring 65 is inserted. The element 62 is rigid with a horizontal beam 66 which extends above the cylinder head 67 substantially parallel to cam shaft 58 and provided with suitable feet 68 fixed to the cylinder head. The element 63 is rigid with semi-spherical head 61 the center of which coincides with axis 53.

The chamber 64 communicates with a pair of mouths located on the outside of element 62 through a conduit composed of a horizontal bore 69 and a vertical bore 70 of member 62. The conduit 70 is closed by a check valve 71. For that purpose, a seating member 72 is held at the upper end of chamber 64 by a cage member 73 engaging internal threads of member 62 and holding the check valve plate 71 in position for cooperation with the seat member 72.

A jacket 74 of a pliable, resilient, oilresistant material, such as synthetic rubber, surrounds the elements 62 and 63 so as to normally cover the mouths of horizontal bore 69 in normally spaced relationship forming an annular space 75. Suitable means are provided for sealing each end of jacket 74 to one of the telescopic elements 62 and 63. The operating space comprised of chamber 64, conduits 70, 69 and space 75 is filled by a liquid, such as oil. The spring 65 is so biassed as to expand the telescopic device to thereby take up any lost motion between the elements 57, 54, 52 and 55. On such expansion of the de vice, liquid will be sucked from the annular space 75 through conduits 69, 70 past check valve 71 into chamber 64, and during the valve opening periods in which stem 55 is depressed by cam 57, rod 54 and lever 52, the liquid filling in chamber 64 will sustain and resist the pressure exerted on telescopic element 63 by spring 59 and cam 57.

Whenever valve 56 is firmly seated as shown in the drawing, however, the element 63 will be relieved of such pressure and then may take up any lost motion by downward movement under the effect of spring 65. Should heat expansion of rod 54 and/or stem 55 or other causes interfere with a firm seating of valve 56 on valve seat 76, however, member 63 would be continuously subjected to the force of spring 59 and would gradually at a very low speed yield to such pressure on account of seepage of liquid past the cylindrical mating faces of elements 63 and 62. Therefore, the telescopic self-adjusting device while completely taking up any lost motion will not jeo pardize the reliable operation of valve 56.

The means for sealing the ends of pliable jacket '74 to the telescopic elements 62 and 63 preferably include a peripheral groove 77 provided in member 62 and 21 peripheral groove 78 provided in member 63, the ends of such jackets extending into said grooves. Preferably, the ends of the jackets are provided with beads engaging the grooves. Moreover, each of the elements 62 and 63 is provided with a suitable shoulder 79 or 80 respectively, confining the groove and engaged by the respective end face of the jacket. In this manner, the outside of the jacket will lie flush with the outside of the respective shoulders '79, 80. For sealing the ends of the jackets in the grooves, preferably hoops 8i and 82 of sheet metal or other suitable material are seated on the associated ends of each jacket 74 and on the outside of shoulders 79, 80 of the telescopic elements.

As shown in the drawing, the jacket 74 bulges outwardly when the telescopic device is more or less contracted. This bulge is preferably so dimensioned that on relative motion of the telescopic elements, the volume of space 75 will change by an amount equalling and offsetting the concomitant opposite change of volume of chamber 64. As a result, a minimum of tension will be set up in the jacket, because any liquid discharged from or sucked into chamber 64 will be taken up or released by jacket 74 owing to the change of its bulge caused by its axial expansion or contraction.

Preferably, one of the telescopic elements, such as 64, is provided with a charge opening closed by a removable plug 83, for instance with a vertical bore communicating with conduit 70. Air discharge ducts 84 may lead from the highest point of the operating spaces 75, 69, 70, 64 to the charge opening so as to permit any air to escape when the device is charged with liquid upon removal of plug 83. in lieu of oil, any other suitable liquid may be used, preferably a liquid having a high viscosity.

in order to prevent an accidental turn of the lever 52 about the axis of the telescopic device, the valve stem 55 is provided with a removable cap 85 having a groove 86 extending in the direction of lever 52 and being engaged by a projection 87 of lever 52. Thus, the right hand arm of lever 52, as viewed in the drawing, and the valve stem have what may be called a splined engagement" which will prevent a relative lateral displacement. The other arm of lever 52 is acted upon by push rod 54 through the intermediary of a universal joint formed by a spherical head 88 engaging a mating semi-spherical depression of lever 52.

While we have described our invention with reference to one specific embodiment thereof, we wish it to be clearly understood that our invention is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

What we claim is:

l. Expandable device for automatically taking up lost motion comprising a pair of elements mounted in telescopic relationship and confining an expandable chamber therebetween, a spring tending to move said elements apart, a conduit in at least one of said elements leading from a mouth located on the outside thereof to said chamber, an inwardly opening check valve cooperating with said conduit, a jacket of pliable material surrounding said elements to cover said mouth in the normally spaced relationship of said elements, means for sealing each end of said jacket to one of said elements, and a liquid in the operating space comprised of said chamber, of said conduit and of the space between said mouth and said jacket, one of said elements being provided with a charge opening left uncovered by said jacket and with at least one duct leading from said charge opening to said operating space, and at least one air discharge duct connecting the highest point of said operating space with said discharge opening, said air discharge duct slanting upwardly towards said opening.

2. Expandable device according to claim 1, wherein each of said elements is provided with an external peripheral groove and an external peripheral shoulder confining one side of the groove, and wherein said jacket includes beads engaging respective grooves, said jacket resting with the ends thereof against said shoulders with the outside of said jacket flush with the outside of said shoulder.

3. Expandable device according to claim 2, further comprising hoops seated on the ends of said jacket and extending over the outside of adjacent shoulders to cover the joint therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,952 Eshbaugh June ll, 1940 2,326,883 Pierce et al Aug. 17, 1943 2,374,508 Smith Apr. 24, 1945 2,433,948 Good Jan. 6, 1948 2,547,798 Truxell, Jr. Apr. 3, 1951 2,654,356 Oldberg Oct. 6, 1953 FOREIGN PATENTS 436,744 Great Britain Oct. 17, I935 

